In a campaign that's supposed to be about an ailing economy, there's just one financial indicator that remains consistently robust: Call it the Gross Political Product.

The latest signal of just how profitable a business politics remains is available on Sunlight's Follow the Unlimited Money, which shows outside spending at nearly $465 million as of Sunday evening. That's more than the total for the entire 2010 campaign, the first that took place following the Supreme Court's landmark Citizens United decision, which allowed corporations and unions to give in unlimited amounts.

This cycle's outside spending mostly comes in the form of "independent expenditures" supporting or opposing political candidates by unions, corporations, trade associations, non-profit groups and super PACs. This money enabled outside groups to run shadow campaigns for or against candidates of their choice, as a look at some of the expenditures reported over the weekend shows. They include:$117,880 from Planned Parenthood for a mailer against Republican presidential nominee Mitt Romney, $5,000 from the Natural Resources Defense Council for plane flyover message against Heather Wilson, the Republican Senate candidate in New Mexico, and $1,735 for a TV ad opposing Sen. Jon Tester, D-Montana, underwritten by a group called America Is Not Stupid, Inc.

But it also includes $4.1 million in expenditures for "electioneering," the term used for ads and political activities that focus on issues and policies in ways that not-so-subtly encourage voters to support or oppose a particular candidate.

About 78 percent of this year's outside spending can be attributed to the Citizens United effect:

$272 million from super PACs, entities that came into being only following the Supreme Court's January 2010 decision, and

almost $93 million from corporations, trade associations and non-profits — groups that the Supreme Court ruling allowed to spend in unlimited amounts and that, because of their tax status, are not required to disclose the source of their funds to the Federal Election Commission.

A deeper dive into the data shows that the latest uptick in outside spending is focused on congressional races: Even in presidential battleground states, almost all the spending by outside groups is focused on House and Senate candidates. The groups providing the cash run the gamut of outside spending organizations and have widely different strategies:

In North Carolina on Friday, the National Republican Congressional Committee — one of the party committees that have so far spent more than $66 million in the 2012 campaign — dumped more than $350,000 into two House races, trying to defeat Democratic Reps. Larry Kissell and Mike McIntyre

In Missouri, Working America — one of the committees that does not file with the FEC and therefore, does not have to disclose donors — has logged hundreds of independent expenditures in the $25-$60 range, all for payments to individuals and expenses such as car rentals and gas, a sign that the group is focusing on an intensive get-out-the-vote effort for Democratic Sen. Claire McCaskill.

Workers Voice, the AFL-CIO's super PAC, is making similar kinds of expenditures in Florida to help Sen. Bill Nelson, a Democrat, and a number of Democratic House candidates.

Republican-leaning independent groups appear to be putting their money into big-dollar expenditures. Crossroads GPS, a non-profit formed after the Citizens United decision by veteran GOP operatives Ed Gillespie and Karl Rove, reported spending more than $400,000 in Nevada last week on a media buy against Rep. Shelley Berkley, the Democratic Senate candidate in the state.

The National Rifle Association on Friday put nearly $200,000 into media buys against two Democratic House candidates, Patrick Kreitlow in the state's 2nd Congressional District and James Wall in the 3rd CD.

In Ohio, the House Majority PAC, a super PAC formed by Democratic operatives to help elect the party's congressional candidates, on Friday reported spending $23,000 on a mailing against Republican Rep. Jim Renacci.